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Lo :18 November 1998 AGE-NC Project No. 98-0483 Low Page 3 of 7 A summary of soil analytical results is presented above in Table 1. TPH-d was detected in one of the ' three soil samples collected from the soil stockpiles. There were no reported detections of TPH-d in any of the soil samples collected beneath the fuel dispenser or USTs. Concentrations of THP-mo" tW were detected in seven of the eight soil samples analyzed. TPH-mo was detected in soil sample TK1-West-15' at concentrations`as high as 14,000 mg/kg. Total xylenes was detected at relatively low concentration in two of the eight soil samples analyzed. Total xylenes was detected in soil sample TK1-West-15' and in one of the three stockpile soil samples analyzed. There were no reported detections of benzene,toluene and ethylbenzene in any of the soil samples analyzed. 1,,,,, Following removal of the USTs and collection of soil samples, the excavations were backfilled to surface grade with clean fill materialAn addition, soil excavated and stockpiled during the UST removal activities was transported under manifest for disposal at Americlean in Silver Springs, h Nevada. 2.3. REGIONAL GEOLOGIC SETTINGLW _ The subject property is located within the northern San Joaquin Valley which comprises part of the Great Valley geomorphic province of California. The San Joaquin Valley is formed by the Great- Valley reatValley geocline, which is a large, elongate, northwest-trending asymmetrical structural trough . (basin). It is bordered by the Coast Ranges to the west,the Klamath Mountains and Cascade Range to the north, and the Sierra Nevada to the east. This trough has been filled with sediments derived from both marine and continental sources.Thickness of the sedimentary fill ranges from thin veneers. along the valley edges to greater than 20,000 feet in the south central portion of the valley. The sedimentary formations range in age from Cretaceous to Recent with the older deposits (Cretaceous E to Eocene) being primarily marine in origin and the younger deposits (Eocene to recent) being primarily continental. Continental-derived sediments were primarily deposited in lacustrine, fluvial, and alluvial environments with sources being the mountain ranges surrounding the valley (Olmsted and Davis, 1961).The subject property is located on unconsolidated and semi-consolidated alluvium, �., lake,playa and terrace deposits of Quaternary age(California Division of Mines and Geology, 1977). 2.4. GROUND WATER DEPTH AND FLOW DIRECTION Based on the San Joaquin County Flood Control-District and Water Conservation District Lines of Equal Depth of Water Wells Fall 1996 map,the estimated depth to ground water in the vicinity of the site is 60 and 70 feet below surface grade(bsg). However, significant ground water recharge has occurred during 1994 through 1998 and ground water depth at the site may be more shallow than �" estimated in 1996. Advanced GeoEnvironmental,Inc.